Method of treating steel.



AUGUSTE J. ROSSI, OF NIAGARA FALLS, NEW YORK, ASSIGNOR TO THE TITANIUM ALLOY MANUFACTURING COMPANY, OF NEW YORK, N. Y., A CORPORATION OF Patented June 4, i912.

MAINE.

. METHOD OF TREATING STEEL.

1,028,389. Specification of Letters Patent.

No Drawing.

To all whom it may concern:

Be it known that I, AUGUSTE J. Rossi, a citizen of the United States, and a resident of Niagara Falls, in the county of Niagara and State of New York, have invented a certain new and useful Method of Treating Steel, of which the following is a specification.

The objects of my present invention comprise the imparting to steel, particularly rails employed in railroad construction as the bearing surface for locomotives, motors and rolling stock, not only greater hardness than heretofore, but also at the same time greater endurance and greater capacity to resist shock and vibrations, and I attain these objects by the methods of treatment hereinafter described.

The present requirements specified as indispensable in rails of the type referred to embrace the greatest possible hardness or capacity to resist frictional wear, and not only this but the greatest possible endurance so called, being the capacity to endure, without undue disintegration, repeated momentary shocks under high pressures in various directions, and also the capacity to resist the disintegrating effects imparted by vibration. Hitherto it has been well understood that hardness is imparted to such rails substantially proportionately totheir content of carbon, but the desired increase of said content has proved impossible beyond certain comparatively low limits even by resort to addition of certain percentages of manganese, say about 1% or less, notwithstanding which additions, or even greater additions, of manganese, it has nevertheless still proved impossible in practice to incorporate more than say 0.5% to 0.6% of-carbon without imparting prohibitory brittleness. The presence of the manganese, up to a certain point, appears to overcome the brittleness imparted by the carbon to the extent of permitting the rail to be rolled successfully, and without the said addition of manganese in sufficient amount rail material containing as high as the aforesaid 0.5% and 0.6% of carbon has proved impossible to be rolled. It appears however to be understood at present that said use of manganese imparts to the product some undesirable qualities, as for instance probably retention therein of sulfid of manganese, to which has been attributed evil effects. Moreover, as above Application filed January 6, 1911. Serial No. 601,161.

implied, the employment of manganese for this specific purpose is limited, manganese being unable to counteract sufliciently the brittleness imparted by the carbon in higher than the above stated percentages.

My researches have demonstrated thatby the presence of titanium in lieu of manganese for the specific purpose for which the latter has been employed as aforesaid, not only is the brittleness attributable to, I may say, unlimited increase of carbon perfectly controllable, it being thus possible to dispense entirely with manganese for the purpose stated, but also that the titanium, in proper amounts, is capable of imparting to the resulting rail having substantially any desired content of carbon, not only increased elastic limit, elongation and ultimate strength, as hitherto understood to result from purifying action of titanium, but also, and particularly, as I have recently demonstrated, certain additional properties and characteristics satisfying the present re quirements in rails as above stated, to wit, unprecedented hardness and also endurance and capacity to resist vibration. I believe these last mentioned characteristics of the rail embodying titanium to be due in part to the combined presence therein of the said high precentages of carbon and a sufficient amount of titanium to overcome the brittleness imparted by such carbon contents. At all events it will be understood that thesuperior capacity of the rail to resist success- .fully attrition is due in part to the presence of the high percentage of carbon admissible by my treatment, whereas, on the other hand, this characteristic would, however desirable,

prove impracticable for rolling and other-- wise without the presence of the titanium, that is to say its novel effect when coacting with novel percentages of carbon upon the structure of the steel, as for instance the groupings of its ferrite; pearlite and cementite, which results in overcoming its otherwise prohibitory brittleness and imparting thereto, in addition to hardness, the endurance and resistance to vibration referred to.

It will be understood that my present invention comprises not only the imp-rovement of steel, generally speaking, by adding thereto while molten a quantity of titanium suflicient to chemically combine with undesired elements and compounds present and thus insure a resulting product free from such impurities comprising slags and containing also substantially no, or traces only of, titanium whereby certain highly desirable characteristics are imparted due to the complete purification of the metal, such being increased elastic limit, elongation and ultimate strength. On the contrary my present invention comprises not only the improvement of the metal by purification referred to, but also, and particularly in addition to this, the imparting to steel rails specifically of qualities unattainable by the said purification merely, and the accomplishment of this novel result by means of increasing the carbon content of said rails to any degree desired above that hitherto practicable, and by additions of titanium not only sulficient to purify the metal as aforesaid but also to insure retention in the final product of an amount of titanium suflicient, in combination with said carbon, to impart the increased hardness and also the increased endurance and resistance to vibration which it is my object to secure.

My present invention is practised as follows: To the molten steel from which the rails are to be ultimately rolled, said steel containing the desired high percentage of carbon, which may be as high as 0.85% oras much higher as required, I add a relatively small quantity of metallic titanium, preferably in the form of the alloy of that metal with iron known as ferro-titanium, which may be produced for instance as per Letters Patent No. 609,466, granted to me August 23,1898. The said amount of titanium is proportioned to satisfy the chemical aflinities of previously ascertained undesired elements and compounds contained in or absorbed by the steel and thus secure their removal including slags by the process for which Letters Patent No. 1,003,805 were granted to me on September 19, 1911. In this instance however I also intentionally add to the said amount of titanium so ascertained enough additional titanium to insure the retention in the final product-,after the titanium has performed its aforesaid purifying function, of a certain amount of that metal being no more than suflicient to impart to the final product such endurance and resistance to vibration as is required to overcome completely the otherwise prohibitory brittleness to be expected from the presence of the particular content of carbon em-,

ployed. Anything in excess of the amount of titanium thus specified will prove not only a waste of the metal for the particular purpose in hand, but also, in my opinion, possibly deleterious as imparting character istics and qualities as yet undetermined and which are likely to prove ofdecided disadvantage in steel rails. It will be apparent that the aggregate amount of titanium thus added to thesteel as aforesaid will depend upon the particular requirements of each case as determined not only by knowledge of the character and extent of the impurities contained in the steel but also upon the percentage of carbon employed, and furthermore upon tests of specimens of each type of steel treated to determine the amount of titanium required in the final productto insure, notwithstanding the high carbon content, absence of brittleness and such endurance and resistance to vibration as may be required. I prefer to introduce the titanium in the form of its alloy with a ferrometal, as aforesaid, the said alloy containing from 10 to 12% or thereabout of metallic titanium. In some instances I have found that as little as one-third of 1% of the said alloy last mentioned is sufficient to insure by its chemical combination with undesired elements and compounds entire removal of the latter including slags, and that in such instances in which the steel treatedcontained as high as 0.85% of carbon the further addition of from of 1% to 1}% of the said alloy has proved sufficient to overcome all brittleness attributable to said 0.85% carbon and also to impart to the resultingrails qualities of endurance and resistance to vibration hitherto I believe unattained and otherwise unattainable. For example in one instance in which the carbon content of the steel was 0.85% I added thereto while molten altogether about 1% to'li-% of my alloy of titanium with iron, ferro-titanium, containing 10 to 12% of'titanium. The rails from this steel rolled perfectly, and under the vibration test withstood oversixty million vibrations without impairment; also on the breaking test the said rails proved very superior under the severest strains, for instance between supports five feet apart enduring several central impacts of a ton weight falling thereon 14 to 16 feet, whereas the tests for hardness disclosed that the surfaces of said rails were from 200 to 300 per cent. harder than the previously best approved so-called'ha'rd carbon rails analyzing at 0.50% to 0.60% carbon, 0.85% manganese and 010% silicon.

I refrain from specifying more fully the method of adding the ferro-titanium to the steel bath as this is already well understood in the art.. The .bath being'mainta-ined at the melting point of steel, the titanium so introduced in alloy with ferro-metal dissolves therein promptly andperforms its functions on the metal and its impurities as aforesaid. Recent microscopicand other tests have demonstrated that the effect of the residual titanium introduced as per my present invention as aforesaid is apparently to change in important and beneficial particulars the structure of the steel as regards extent of ferrite and cementite and .also

' the presence of any manganese as usually.

7 ing less than 1%.

While the beneficial result of my novel method appears attributable to the combined effect of a high percentage of carbon with a small percentage of titanium in the resulting. rail product, I may also in some cases employ with said high percentages of carbon and low percentages of titanium characterizing my present invention a small amount of manganese, but very much less than formerly required to overcomebrittleness imparted by a much lower than 0.50% carbon content. For example in some instances I have thus added manganese so. as to have in the finalrail product not to exceed 0.60% to 0.18% of manganese. In fact in some special types of steel the presence of a thus minute contentof manganese as compared with that formerly used and indispensable may prove of advantage for special purposes. I do not however regard essential to the attainment of the best results from my aforesaid method of treatment, my tests disclosing possession of the desirable novel qualities and characteristics above described by steel containing no manganese. f p

I am aware that heretofore titanium either by itself, or, more usually, in combination with other elements hostile to my present purpose, has been retained in final steel products for the purpose of producing what are now well known in the art as alloyed steels, z'. e. steels which owe their distinguishing properties chiefly to the presence of a thereto added and therein retained element, or elements, other-- than carbon. But, on the contrary, a distinguishing feature of my present invention is the augmentation of the carbon content, in steel, beyond What has been previously deemed practicable and this for the purpose of imparting to the final product, in proportionally higher degree than heretofore, distinguishing properties due to presence of'high percentages of carbon, my addition and retention of titanium in such product being in aid of such' augmentation of carbon, and for the consists in incorporating carbon in quantity sufficient to produce any desired degree of hardness and to the molten product'adding titanium in quantity sufficient to prevent any undesired brittleness in the resulting steel product characterized as containing titanium and as unalloyed with other metal, substantially as described.

, 2. The method of treating steel which consists in incorporating carbon in quantity sufficient to produce any desired degree of hardness and to the molten product adding titanium in quantity sufficient to prevent any undesired brittleness in the resulting steel product characterized as containing titanium less than 0.50 per cent. and as unalloyed with other metal, substantially as described.

AUGUSTE J. ROSSI.

Witnesses:

WALTER D. EDMONDS, GEORGE G. MEASURES. 

